1. Filed of the Invention
The present invention relates to toroidal engines, toroidal compressors or toroidal generators wherein an assembly of pistons orbits continuously within a toroidal chamber about the central axis of the toroid. More particularly, the invention relates to improvements on engines and compressors, of this kind whereby the displacement volume of the engine or compressor may be selectively varied.
2. Description of the Prior Art
The conventional technology of internal combustion engines such as automobile engines is the reciprocating piston engine, in which a combination of connecting rod(s) and crank shaft is used to convert reciprocating motion of a piston into rotary motion.
It is currently widely recognized in industries such as transportation, that it would be highly desirable to produce internal combustion engines having variable displacement (sometimes referred to as “displacement on demand”). The ultimate objective is to improve fuel economy and reduce emissions in vehicles and equipment, without an unacceptable degree of sacrifice in performance and quick response.
A number of attempts have been made to achieve variable displacement in reciprocating piston engines. For the most part, these amount to the sequenced deactivation of several cylinders so that they do not consume any fuel and do not contribute to the power during low power operations. An example of a method and apparatus for deactivating and reactivating cylinders for an engine with displacement on demand is to be found in U.S. Patent Publication No. 2002/0162540 A1 (Mathews et al.).
Efficiency of cylinder deactivation as a route to achieving variable displacement in conventional reciprocating piston engines is hindered, since the deactivated pistons still have to be reciprocated (as a consequence of the crank shaft assembly), leading to friction. Further, the ignition and fuel injection of the deactivated cylinders have to be disengaged, making the control system still more complicated. Further still, the displacement can only be varied in certain steps, depending upon how many cylinders are deactivated. These are serious limitations and constraints upon variable displacement internal combustion engines.
As discussed in detail below, I have found that a toroidal piston engine, providing revolving pistons mounted to a central disk, is more easily adapted to selectively changing the displacement or size of the engine.
Like all positive displacement combustion engines, the toroidal engine must incorporate means both for compressing the intake charge and for containing the hot expanding gases that are generated by combustion. A number of attempts have been made to provide for some sort of on/off valving mechanism for the cylinder, to intercept the path of the advancing piston, then to retract and allow the piston to pass by, and thereafter to close behind the piston.
In the rotary engine described and claimed in my U.S. Pat. No. 6,546,908, a rotating disk valve perpendicular to the toroid includes a cutout portion which periodically traverses the toroidal chamber to allow passage of a piston does duty as the cylinder valving means. Compression occurs as a piston in the toroid approaches the disk valve, having earlier taken in fresh air from an inlet on the toroidal chamber. The disk valve and the piston form a closed part-toroidal chamber allowing compression as the advancing piston reduces the trapped air volume during the stroke. Most of the compressed air is then ducted into a combustion chamber, where fuel is injected and ignition takes place. While combustion takes place, the piston passes by the disk valve and the high pressure combustion gases are then ducted into the chamber behind the closing disk valve, pushing the piston forward as they expand, so producing rotation and power. Accordingly, each piston exposed to the expanding gases produces a power stroke.
U.S. Pat. No. 6,546,908 is hereby incorporated by reference for its teachings on the structure and operation of rotary engines and compressors generally. The principal objective attained by the toroidal engine which is the subject matter of this patent is to minimize residual volumes between the piston and the closed disk valve, through alterations to the geometry of the chamber section formed between valve and piston, and thereby to attain significant improvements in performance. For that reason, the engine of U.S. Pat. No. 6,546,908 was described as a “variable geometry” toroidal engine (VGT engine).
I have now developed a controlled air input and outlet valving system whereby variable displacement capability may be imparted to any toroidal internal and external combustion engine or toroidal compressor. Because toroidal engines do not employ the crank shaft/connecting rod/piston assembly of conventional reciprocating piston engines, there is no requirement for a complex and inefficient sequence of cylinder deactivation. I have discovered that stroke length variation in a toroidal engine incorporating the valving system of my invention may be achieved by the selective opening of intake port valves that determine when the compression stroke starts and exhaust port valves to determine when the expansion stroke (power stroke) has ended.